If you have an Android phone you’ve likely installed at least one app from the Market. It was an easy process: open the Market, find the app you’re looking for, tap it, then tap “Buy” or “Install”.

What if the app isn’t in the Market?

iPhone users are out of luck (unless they JailBreak), but Android users can install any application that’s compatible with their phone, just by installing the .apk.

Android applications are packaged in .apk files (which are similar to Windows Mobile .cab files). If you have a web page that links to the .apk you can tap the link to download and install it (you can also install a .apk from your sdcard by browsing to and tapping on it using a file manager such as AndExplorer).

Since files distributed in this method have not been “blessed” by the keepers of the Market you will be presented with an “Install blocked” dialog box. You can Cancel, or continue by tapping the Settings button.

On the Application Settings screen you’ll see an item titled “Unknown sources” which allows you to install non-Market applications. If you’re still sure you want to do this, tap the checkbox.

At this point you’re given one my chance to back out. If you want to continue, read the dialog and tap OK.

You are now able to install non-Market apps, but the app you wanted to install hasn’t been installed yet. You’ll need to restart the installation process for that app, but it should succeed now.

Now that you can install whatever apps you want to, you might wonder where to get them.

Where Can I Find non-Market Apps?

Apps can be pulled from SDK or ROM dumps (but these .apks may not work on your device; don’t worry, they’ll fail to install without harming anything if you find and try to install incompatible .apks). You can also find apps on app developer’s websites. Most commonly, these apps are either beta or specialty apps that a developer is trying out before investing the time (and money) to have the app listed in the official Android Market.

The most popular source of non-Market apps that’ I’ve been able to find has been from “Market Alternative” apps, which are alternative marketplaces to the “official” Android Market.

One such “alternative market” app is SlideME Application Manager (“SAM”). Once installed, this app give you a similar interface and experience as the stock Android Market. Other marketplaces, such as MiKandi (NSFW), are geared to the “adult app” audience and offer adult-oriented apps that either have been or would be rejected from the stock Android Market.

Remember, just like the warnings said, a developer can write an app that will do virtually anything, and by allowing your Android to install any .apk you are turning off one level of protection. That having been said, you are now able to install any application that you want, and don’t need to go to the trouble of jailbreaking (or rooting) your phone.

If you are a developer and have your apps available via .apk download, please comment! We’d like to know what your application is, what it does, and why you’re not distributing it through the Market.